Windows are usually the weakest point in a home's thermal envelope, and Maryland asks a lot of them across the year: humid, sunny summers followed by genuinely cold winters. Solar control film works on the summer side of that equation, reducing the heat that arrives through the glass so air conditioning isn't fighting the afternoon sun in every sun-facing room. The comfort difference tends to show up first in the rooms people avoid in July. Film is applied to the glazing you already have, which makes it a far smaller job than replacing windows, and it can be a sensible option where the frames and units are otherwise sound. The right choice depends on what that glazing is, so identify whether you have single panes, older double-glazed units or newer coated glass before settling on a film. A Kepler dealer can check that with you, discuss which rooms matter most and recommend a film and shade that suits the house rather than a blanket specification.